Kavli Affiliate: Robert A. Simcoe
| First 5 Authors: Jack Higginson, Jack Higginson, , ,
| Summary:
We investigate the association between galaxies and neutral OI absorption
systems at z~6, which trace metal-enriched gas during the epoch of
reionization. We identify 40 galaxies across six quasar fields, residing in 15
overdensities within 300 kpc of the background sightlines. Five OI absorption
systems are associated with five of these overdensities, yielding a covering
fraction of $0.27^+0.13_-0.10$ within 300 kpc. The absorption occurs beyond
typical virial radii, indicating that the gas traces extended overdensity
environments rather than individual galaxy halos, unlike the z~0 CGM which is
largely bound to halos. These galaxy-associated absorbers account for
$sim35%$ of all OI systems seen in blind quasar surveys, implying the
remainder arise in lower-mass galaxies below our detection threshold or in
dense neutral IGM pockets. The CGM around these galaxies contains $gtrsim
2times10^6~M_odot$ of oxygen, comparable to the ISM oxygen mass of the
galaxies themselves, suggesting that the surrounding environment holds as much
metal mass as the galaxies. All five galaxy-associated systems show
significantly higher $log(N_rm CII/N_rm OI)$ ratios than absorbers
lacking galaxy associations. Furthermore, relative abundance ratios ([Si/O],
[C/O]) reveal that four of the five exhibit enrichment patterns consistent with
Population III nucleosynthesis. These rare systems offer a unique window into
the role of first-generation stars in shaping the early metal enrichment of
galaxies and their environments.
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